Nitrification in Pilot-Scale High Rate Algae Ponds Operated as Sequencing Batch Photo-bioreactors for Anaerobically Treated Domestic Wastewater
A.M. Rada-Ariza1*, A. Alfonso-Martínez 1, U. Leshem 3, C.M. Lopez-Vazquez 2, N.P. Van der Steen 1 and P.N.L. Lens1
1 Department of Environmental Engineering and Water Technology, Pollution Prevention and Resource recovery Chair, UNESCO-IHE, Institute for Water Education, 2601 DA Delft, The Netherlands. 2 Department of Environmental Engineering and Water Technology, Sanitary Engineering Chair, UNESCO-IHE, Institute for Water Education, 2601 DA Delft, The Netherlands. 3 Aquanos Ltd, 4 HaDekel st, Shoshanalt HaAmakim, 4298400 Israel
(free)
The concept of the photo-activated sludge (PAS) system for ammonia removal was investigated in pilot-scale high rate algae ponds (HRAPs) operated as sequencing batch reactors located in Israel during winter months. The systems were inoculated with algae and nitrifying bacteria and evaluated for ammonium removal treating anaerobically pre-treated municipal wastewater. Ammonium concentrations below 2.0 mgNH4+-N/L were obtained in the clarified effluent when treating influent concentrations containing up to 54 mgNH4+-N L-1 The average ammonium removal rates ranged in between 0.58-0.69 mgNH4+-N L-1 h-1 with a sludge retention time of 55 days and HRTs of 2.9-3.9 days. The maximum ammonium removal rate achieved in a cycle was of 3.0 mgNH4+-N L-1 h-1, 1.2 hours after influent addition. Based on a nitrogen mass balance, most of the ammonium was removed via nitrification (73-94%), using natural oxygen supply provided by algae. The area requirements ranged between 1.6-2.3 m² P.E-1. and the energy consumption between 0.13 and 0.19 kWh (kgNH4+-N)-1. The PAS system showed promising results and effectiveness of algae/bacteria consortia for ammonium removal in HRAPs; lower energy consumption compared to conventional systems such as activated sludge, and reduced area requirements of conventional HRAPs and conventional algae ponds.
